标题: 新prep2-82 [打印本页]
作者: franciszmy 时间: 2012-10-16 06:51 标题: 新prep2-82
82.
Technological improvements and reduced equipment costs have made converting solar energy directly into electricity far more cost-efficient in the last decade.
However, the threshold of economic viability for solar power (that is, the price per barrel to which oil would have to rise in order for new solar power plants to be more economical than new oil-fired power plants) is unchanged at thirty-five dollars.
Which of the following, if true, does most to help explain why the increased cost-efficiency of solar power has not decreased its threshold of economic viability?
A. The cost of oil has fallen dramatically.
B. The reduction in the cost of solar-power equipment has occurred despite increased raw material costs for that equipment.
C. Technological changes have increased the efficiency of oil-fired power plants.
D. Most electricity is generated by coal-fired or nuclear, rather than oil-fired, power plants.
E. When the price of oil increases, reserves of oil not previously worth exploiting become economically viable.
这题为什么选C呢?
我不太明白段落的意思,我自己的理解为尽管技术改进和设备成本减少使得solar power是合算的,但是其经济可行性没有改变,还是$35.而所谓的经济可行性是每桶石油的价格必须提升,以使得新的solar power工厂比新的oil-fired power工厂更为实惠.
答案的思路是说尽管石油的价格提升了,但是石油工厂的效率也提高了,所以其用油就省了,所以solar power就不经济可行了吗?请NN们指教~~~
作者: EvaCheng 时间: 2012-10-16 21:15
我想知道为什么不能选A。。。
作者: aduoyi 时间: 2012-10-17 06:35
过去: 太阳能发电成本 - 石油发电成本 = 35美圆
现在: 太阳能发电成本下降了, 但仍然 太阳能发电成本 - 石油发电成本 = 35美圆
解释: 石油发电成本也下降了.
而threshold就是两种发电厂的成本之差
A：油价只是衡量threshold一个因素，但是不是确定threshold关键的因素，因为还有别的因素例如人力，原料或者别的什么
而题目中提到说，太阳能转化的效率提高（即成本下降），而threshold不变，那么从公式(3)中就很容易得到：是因为石油转化成电能的成本也降低了（即石油发电效率提高）。
所以选C。
作者: EvaCheng 时间: 2012-10-17 20:58
恩，谢谢解答，我也觉得可能是这个区别
作者: myungryong 时间: 2012-10-18 21:13
我觉得不选A是因为 问题问的是为什么效率的提高没有降低economic viability的门槛，要将两者联系起来，A说oil price 降低了，那太阳能厂就达不到economic viability的门槛，但是它没有将 效率的提高 和门槛的降低联系在一起。 C说oil-fired厂效率也提高了，所以太阳能厂效率的提高还是不能降低门槛 可能是相对的问题吧。
作者: windcolour 时间: 2012-10-20 06:28
请问版主，(that is, the price per barrel to which oil would have to rise in order for new solar power plants to be more economical than new oil-fired power plants) 括号里这句话是不是就是在界定经济准入门槛的含义呢？如果是的话，就以为这太阳能发电能否进入，衡量指标就是这个关于油价上涨。为什么版主认为油价只是一个因素？如果还有其他因素，如人力等，那么这些因素的高低，如人力成本的高低又如何能体现是否达到准入门槛呢？因为衡量指标里并没有这一项
望赐教 谢谢
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